This invention relates generally to the field of recreational watercraft, and more particularly to the hydraulic system for a watercraft, and specifically to a common hydraulic system for providing pressurized fluid to a hydraulic transmission, a power steering unit, and a trim unit of a watercraft.
Attention is directed to the following U.S. Patents which describe the various
Recreational watercraft are generally propelled by an internal combustion engine mounted either inboard to the watercraft or supported outboard on the transom of the watercraft. An inboard engine may be connected to the propeller via a stern drive unit passing through the transom of the watercraft. It is known to provide a power steering system for both inboard and outboard watercraft. Such power steering systems typically include one or more hydraulic cylinders selectively activated by being provided with a pressurized hydraulic fluid via a power steering cylinder valve that is responsive to the movement of a steering wheel. The power steering hydraulic cylinder may be connected to a steering arm which pivots the drive unit about a generally vertical axis, thereby controlling the direction of thrust provided by the propeller. The power steering cylinder valve controls the supply of pressurized hydraulic fluid to the hydraulic cylinder. The operator of the watercraft thus needs only to exert enough effort to operate the power steering cylinder valve and not the total effort required to actually rotate the steering arm. A cooler may be provided to remove heat from the hydraulic fluid generated by the action of the power steering pump.
It is also known to provide a power trim system for both inboard and outboard drive units. A power trim system is used to pivot the propeller about a generally horizontal axis to adjust the vertical drive angle of the propeller with respect to the watercraft. Such rotation of the propeller in the vertical direction permits the angle of thrust to be optimized for both on-plane and off-plane operation of the watercraft. To accomplish the power trim function, pressurized hydraulic fluid may be provided by a reversible pump to a lift cylinder to raise or lower the bottom portion of the drive unit. The trim system may include the capability to lift the propeller completely or nearly out of the water for operation in shallow water and for removal of the watercraft from the water. Such systems are referred to as tilt-trim systems and often include separate hydraulic cylinders for performing the tilt and the trim functions.
It is also known to utilize a hydraulic transmission with an inboard/outboard watercraft. Such transmissions utilize pressurized hydraulic fluid to actuate a shifting mechanism and also to provide lubrication within the transmission. The flow of the hydraulic fluid and the power to operate the shift mechanism is provided by a transmission fluid pump through one or more transmission valves. A cooler is usually provided to maintain the temperature of the transmission fluid below an upper limit in order to protect the transmission components and to prevent premature degradation of the transmission fluid.
Typically, each of the hydraulic systems in a watercraft is a self contained unit, including a reservoir for storing hydraulic fluid, a pump connected to the reservoir for pressurizing the hydraulic fluid, and appropriate valves and interconnecting typing. Each system is provided with both fill and vent connections. The hydraulic fluid in the power steering and hydraulic transmission circuits may become heated due to the operation of the respective pump, and individual coolers are normally provided to remove heat from each of these fluid systems. The fluid level in each of the hydraulic systems must be checked periodically to ensure that an adequate supply of hydraulic fluid is available for operation of the watercraft. Access to the various fluid fill locations and associated dipstick level indicators is often restricted, causing some watercraft operators to forego the appropriate schedule for fluid fill verification. As a result, equipment damage and/or unsafe operating conditions may result from the operation of the watercraft with an inadequate hydraulic fluid supply in one or more of the hydraulic systems.
Thus there is a particular need for a watercraft having hydraulic systems that are easy to inspect for proper fill level. There is also a need for a simple and less expensive hydraulic fluid supply apparatus for the various hydraulic systems on-board a watercraft. Furthermore, there is a need for a watercraft that is less susceptible to damage resulting from the operation of the watercraft with an inadequate hydraulic fluid supply level in one or more of its hydraulic systems.
Accordingly, a common fluid pressure supply apparatus is described herein for a watercraft having a drive unit including a hydraulic transmission, a hydraulically operated power steering apparatus attached to the drive unit for steering the water craft, and a hydraulically operated trim apparatus attached to the drive unit for raising and lowering the drive unit with respect to the watercraft. The watercraft includes a transmission housing reservoir for containing hydraulic fluid; a transmission pump having an inlet in fluid communication with the transmission housing reservoir and an outlet for providing pressurized hydraulic fluid to the hydraulic transmission, and a fluid return path between the hydraulic transmission and the transmission housing reservoir; a power steering pump reservoir having an inlet in fluid communication with the transmission housing reservoir; a power steering pump having an inlet in fluid communication with the power steering pump reservoir and an outlet for providing pressurized hydraulic fluid to the power steering apparatus, and a fluid return path between the power steering apparatus and the transmission housing reservoir; a trim pump reservoir having an inlet in fluid communication with the transmission housing reservoir; a trim pump having an inlet in fluid communication with the trim pump reservoir and an outlet for providing pressurized hydraulic fluid to the trim apparatus, and a fluid return path between the trim apparatus and one of the trim reservoir and the transmission housing reservoir. The fluid pressure supply apparatus may further include a fill vessel having a low point outlet in fluid communication with each of the power steering pump reservoir and the trim pump reservoir, and having a high point outlet in fluid communication with each of the transmission housing reservoir, the power steering pump reservoir and the trim pump reservoir.